I've been working with the iTunes Store RSS feed and I've noticed that in certain instances, the number of apps being returned doesn't match up with the number of results that I'm requesting. For instance, here is the feed for the top 300 free weather iPad apps for New Zealand:
http://itunes.apple.com/nz/rss/topfreeipadapplications/limit=300/genre=6001/json
I only see 251 apps being returned here. My hunch is that the feed is only returning the apps from this list that are available for sale in the US, since this is where I am, but I haven't seen any documentation one way or another on this. Does anyone know if this is in fact the case?
Note: I'm aware of the issue with the RSS feed for 'New Apps', 'New Free Apps', and 'New Paid Apps' completely ignoring the limit parameter, but this behavior, while disappointing, is at least documented here: http://www.apple.com/itunes/affiliates/resources/blog/introduction---rss-feed-generator.html
Revisiting this issue again, I realized that what I wrote above in my previous comment under user1347544's answer is not correct. I chose Free Weather iPad Apps, not 'Top' Free Weather iPad Apps. So that made me think that 'Top' has a different meaning than what I was originally thinking. I tried a new search in the iTunes App Store: Top Paid iPad Catalog Apps, with my country set to NZ. This time the list displayed 43, same as what the RSS feed displays. However, a search for Paid iPad Catalog Apps for sale in NZ returns 317 results. What I had been thinking was that because there are 317 results total, when I ask for a list of the 'Top' 300, I should get back 300, since there are at least 300 results in that category. However, it seems that for an app to be part of a 'Top' list, it has to meet a certain criteria on number of downloads. This wasn't apparent to me when I first started working with these feeds, although as I'm writing this answer, it definitely makes sense that the 'Top' lists would work this way.